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Searching PubMed: Literature Reviews

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Section Objective

What is a literature review, clearly stated research question, search terms, searching worksheets, boolean and / or.

The content in the Literature Review section defines the literature review purpose and process, explains using the PICO format to ask a clear research question, and demonstrates how to evaluate and modify search results to improve the accuracy of the retrieval.

A literature review seeks to identify, analyze and summarize the published research literature about a specific topic.  Literature reviews are assigned as course projects; included as the introductory part of master's and PhD theses; and are conducted before undertaking any new scientific research project.

The purpose of a literature review is to establish what is currently known about a specific topic and to evaluate the strength of the evidence upon which that knowledge is based. A review of a clinical topic may identify implications for clinical practice. Literature reviews also identify areas of a topic that need further research.

A systematic review is a literature review that follows a rigorous process to find all of the research conducted on a topic and then critically appraises the research methods of the highest quality reports. These reviews track and report their search and appraisal methods in addition to providing a summary of the knowledge established by the appraised research.

The UNC Writing Center provides a nice summary of what to consider when writing a literature review for a class assignment. The online book, Doing a literature review in health and social care : a practical guide (2010), is a good resource for more information on this topic.

Obviously, the quality of the search process will determine the quality of all literature reviews. Anyone undertaking a literature review on a new topic would benefit from meeting with a librarian to discuss search strategies. A consultaiton with a librarian is strongly recommended for anyone undertaking a systematic review.

Use the email form on our Ask a Librarian page to arrange a meeting with a librarian.

The first step to a successful literature review search is to state your research question as clearly as possible.

It is important to:

  • be as specific as possible
  • include all aspects of your question

Clinical and social science questions often have these aspects (PICO):

  • People/population/problem  (What are the characteristics of the population?  What is the condition or disease?)
  • Intervention (What do you want to do with this patient?  i.e. treat, diagnose)
  • Comparisons [not always included]  (What is the alternative to this intervention?  i.e. placebo, different drug, surgery)
  • Outcomes  (What are the relevant outcomes?  i.e. morbidity, death, complications)

If the PICO model does not fit your question, try to use other ways to help be sure to articulate all parts of your question. Perhaps asking yourself Who, What, Why, How will help.  

Example Question:  Is acupuncture as effective of a therapy as triptans in the treament of adult migraine?

Note that this question fits the PICO model.

  • Population: Adults with migraines
  • Intervention: Acupuncture
  • Comparison: Triptans/tryptamines
  • Outcome: Fewer Headache days, Fewer migraines

A literature review search is an iterative process. Your goal is to find all of the articles that are pertinent to your subject. Successful searching requires you to think about the complexity of language. You need to match the words you use in your search to the words used by article authors and database indexers. A thorough PubMed search must identify the author words likely to be in the title and abstract or the indexer's selected MeSH (Medical Subject Heading) Terms.

Start by doing a preliminary search using the words from the key parts of your research question.

Step #1: Initial Search

Enter the key concepts from your research question combined with the Boolean operator AND. PubMed does automatically combine your terms with AND. However, it can be easier to modify your search if you start by including the Boolean operators.

migraine AND acupuncture AND tryptamines

The search retrieves a number of relevant article records, but probably not everything on the topic.

Step #2: Evaluate Results

Use the Display Settings drop down in the upper left hand corner of the results page to change to Abstract display.

Review the results and move articles that are directly related to your topic to the Clipboard .

Go to the Clipboard to examine the language in the articles that are directly related to your topic.

  • look for words in the titles and abstracts of these pertinent articles that differ from the words you used
  • look for relevant MeSH terms in the list linked at the bottom of each article

The following two articles were selected from the search results and placed on the Clipboard.

   

Here are word differences to consider:

  • Initial search used acupuncture. MeSH Terms use Acupuncture therapy.
  • Initial search used migraine.  Related word from MeSH Terms is Migraine without Aura and Migraine Disorders.
  • Initial search used tryptamines. Article title uses sumatriptan. Related word from MeSH is Sumatriptan or Tryptamines.

With this knowledge you can reformulate your search to expand your retrieval, adding synonyms for all concepts except for manual and plaque.

#3 Revise Search

Use the Boolean OR operator to group synonyms together and use parentheses around the OR groups so they will be searched properly. See the image below to review the difference between Boolean OR / Boolean AND.

Here is what the new search looks like:

(migraine OR migraine disorders) AND (acupuncture OR acupuncture therapy) AND (tryptamines OR sumatriptan)

  • Search Worksheet Example: Acupuncture vs. Triptans for Migraine
  • Search Worksheet

Venn diagram with all segments highlighted

Combining search words with the search.  
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Reviewing literature for research: Doing it the right way

Shital amin poojary.

Department of Dermatology, K J Somaiya Medical College, Mumbai, Maharashtra, India

Jimish Deepak Bagadia

In an era of information overload, it is important to know how to obtain the required information and also to ensure that it is reliable information. Hence, it is essential to understand how to perform a systematic literature search. This article focuses on reliable literature sources and how to make optimum use of these in dermatology and venereology.

INTRODUCTION

A thorough review of literature is not only essential for selecting research topics, but also enables the right applicability of a research project. Most importantly, a good literature search is the cornerstone of practice of evidence based medicine. Today, everything is available at the click of a mouse or at the tip of the fingertips (or the stylus). Google is often the Go-To search website, the supposed answer to all questions in the universe. However, the deluge of information available comes with its own set of problems; how much of it is actually reliable information? How much are the search results that the search string threw up actually relevant? Did we actually find what we were looking for? Lack of a systematic approach can lead to a literature review ending up as a time-consuming and at times frustrating process. Hence, whether it is for research projects, theses/dissertations, case studies/reports or mere wish to obtain information; knowing where to look, and more importantly, how to look, is of prime importance today.

Literature search

Fink has defined research literature review as a “systematic, explicit and reproducible method for identifying, evaluating, and synthesizing the existing body of completed and recorded work produced by researchers, scholars and practitioners.”[ 1 ]

Review of research literature can be summarized into a seven step process: (i) Selecting research questions/purpose of the literature review (ii) Selecting your sources (iii) Choosing search terms (iv) Running your search (v) Applying practical screening criteria (vi) Applying methodological screening criteria/quality appraisal (vii) Synthesizing the results.[ 1 ]

This article will primarily concentrate on refining techniques of literature search.

Sources for literature search are enumerated in Table 1 .

Sources for literature search

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PubMed is currently the most widely used among these as it contains over 23 million citations for biomedical literature and has been made available free by National Center for Biotechnology Information (NCBI), U.S. National Library of Medicine. However, the availability of free full text articles depends on the sources. Use of options such as advanced search, medical subject headings (MeSH) terms, free full text, PubMed tutorials, and single citation matcher makes the database extremely user-friendly [ Figure 1 ]. It can also be accessed on the go through mobiles using “PubMed Mobile.” One can also create own account in NCBI to save searches and to use certain PubMed tools.

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PubMed home page showing location of different tools which can be used for an efficient literature search

Tips for efficient use of PubMed search:[ 2 , 3 , 4 ]

Use of field and Boolean operators

When one searches using key words, all articles containing the words show up, many of which may not be related to the topic. Hence, the use of operators while searching makes the search more specific and less cumbersome. Operators are of two types: Field operators and Boolean operators, the latter enabling us to combine more than one concept, thereby making the search highly accurate. A few key operators that can be used in PubMed are shown in Tables ​ Tables2 2 and ​ and3 3 and illustrated in Figures ​ Figures2 2 and ​ and3 3 .

Field operators used in PubMed search

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Boolean operators used in PubMed search

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PubMed search results page showing articles on donovanosis using the field operator [TIAB]; it shows all articles which have the keyword “donovanosis” in either title or abstract of the article

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PubMed search using Boolean operators ‘AND’, ‘NOT’; To search for articles on treatment of lepra reaction other than steroids, after clicking the option ‘Advanced search’ on the home page, one can build the search using ‘AND’ option for treatment and ‘NOT’ option for steroids to omit articles on steroid treatment in lepra reaction

Use of medical subject headings terms

These are very specific and standardized terms used by indexers to describe every article in PubMed and are added to the record of every article. A search using MeSH will show all articles about the topic (or keywords), but will not show articles only containing these keywords (these articles may be about an entirely different topic, but still may contain your keywords in another context in any part of the article). This will make your search more specific. Within the topic, specific subheadings can be added to the search builder to refine your search [ Figure 4 ]. For example, MeSH terms for treatment are therapy and therapeutics.

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PubMed search using medical subject headings (MeSH) terms for management of gonorrhea. Click on MeSH database ( Figure 1 ) →In the MeSH search box type gonorrhea and click search. Under the MeSH term gonorrhea, there will be a list of subheadings; therapy, prevention and control, click the relevant check boxes and add to search builder →Click on search →All articles on therapy, prevention and control of gonorrhea will be displayed. Below the subheadings, there are two options: (1) Restrict to medical subject headings (MeSH) major topic and (2) do not include MeSH terms found below this term in the MeSH hierarchy. These can be used to further refine the search results so that only articles which are majorly about treatment of gonorrhea will be displayed

Two additional options can be used to further refine MeSH searches. These are located below the subheadings for a MeSH term: (1) Restrict to MeSH major topic; checking this box will retrieve articles which are majorly about the search term and are therefore, more focused and (2) Do not include MeSH terms found below this term in the MeSH hierarchy. This option will again give you more focused articles as it excludes the lower specific terms [ Figure 4 ].

Similar feature is available with Cochrane library (also called MeSH), EMBASE (known as EMTREE) and PsycINFO (Thesaurus of Psychological Index Terms).

Saving your searches

Any search that one has performed can be saved by using the ‘Send to’ option and can be saved as a simple word file [ Figure 5 ]. Alternatively, the ‘Save Search’ button (just below the search box) can be used. However, it is essential to set up an NCBI account and log in to NCBI for this. One can even choose to have E-mail updates of new articles in the topic of interest.

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Saving PubMed searches. A simple option is to click on the dropdown box next to ‘Send to’ option and then choose among the options. It can be saved as a text or word file by choosing ‘File’ option. Another option is the “Save search” option below the search box but this will require logging into your National Center for Biotechnology Information account. This however allows you to set up alerts for E-mail updates for new articles

Single citation matcher

This is another important tool that helps to find the genuine original source of a particular research work (when few details are known about the title/author/publication date/place/journal) and cite the reference in the most correct manner [ Figure 6 ].

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Single citation matcher: Click on “Single citation matcher” on PubMed Home page. Type available details of the required reference in the boxes to get the required citation

Full text articles

In any search clicking on the link “free full text” (if present) gives you free access to the article. In some instances, though the published article may not be available free, the author manuscript may be available free of charge. Furthermore, PubMed Central articles are available free of charge.

Managing filters

Filters can be used to refine a search according to type of article required or subjects of research. One can specify the type of article required such as clinical trial, reviews, free full text; these options are available on a typical search results page. Further specialized filters are available under “manage filters:” e.g., articles confined to certain age groups (properties option), “Links” to other databases, article specific to particular journals, etc. However, one needs to have an NCBI account and log in to access this option [ Figure 7 ].

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Managing filters. Simple filters are available on the ‘search results’ page. One can choose type of article, e.g., clinical trial, reviews etc. Further options are available in the “Manage filters” option, but this requires logging into National Center for Biotechnology Information account

The Cochrane library

Although reviews are available in PubMed, for systematic reviews and meta-analysis, Cochrane library is a much better resource. The Cochrane library is a collection of full length systematic reviews, which can be accessed for free in India, thanks to Indian Council of Medical Research renewing the license up to 2016, benefitting users all over India. It is immensely helpful in finding detailed high quality research work done in a particular field/topic [ Figure 8 ].

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Cochrane library is a useful resource for reliable, systematic reviews. One can choose the type of reviews required, including trials

An important tool that must be used while searching for research work is screening. Screening helps to improve the accuracy of search results. It is of two types: (1) Practical: To identify a broad range of potentially useful studies. Examples: Date of publication (last 5 years only; gives you most recent updates), participants or subjects (humans above 18 years), publication language (English only) (2) methodological: To identify best available studies (for example, excluding studies not involving control group or studies with only randomized control trials).

Selecting the right quality of literature is the key to successful research literature review. The quality can be estimated by what is known as “The Evidence Pyramid.” The level of evidence of references obtained from the aforementioned search tools are depicted in Figure 9 . Systematic reviews obtained from Cochrane library constitute level 1 evidence.

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Evidence pyramid: Depicting the level of evidence of references obtained from the aforementioned search tools

Thus, a systematic literature review can help not only in setting up the basis of a good research with optimal use of available information, but also in practice of evidence-based medicine.

Source of Support: Nil.

Conflict of Interest: None declared.

Literature Searching

In this guide.

  • Introduction
  • Steps for searching the literature in PubMed
  • Step 1 - Formulate a search question
  • Step 2- Identify primary concepts and gather synonyms
  • Step 3 - Locate subject headings (MeSH)
  • Step 4 - Combine concepts using Boolean operators
  • Step 5 - Refine search terms and search in PubMed
  • Step 6 - Apply limits

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Steps for Searching the Literature

Searching is an iterative process and often requires re-evaluation and testing by adding or changing keywords and the ways they relate to each other. To guide your search development, you can follow the search steps below. For more information on each step, navigate to its matching tab on the right menu. 

1. Formulate a clear, well-defined, answerable search question

Generally, the basic literature search process begins with formulating a clear, well-defined research question. Asking the right research question is essential to creating an effective search. Your research question(s) must be well-defined and answerable. If the question is too broad, your search will yield more information than you can possibly look through.

2. Identify primary concepts and gather synonyms

Your research question will also help identify the primary search concepts. This will allow you to think about how you want the concepts to relate to each other. Since different authors use different terminology to refer to the same concept, you will need to gather synonyms and all the ways authors might express them. However, it is important to balance the terms so that the synonyms do not go beyond the scope of how you've defined them.

3. Locate subject headings (MeSH)

Subject databases like PubMed use 'controlled vocabularies' made up of subject headings that are preassigned to indexed articles that share a similar topic. These subject headings are organized hierarchically within a family tree of broader and narrower concepts. In PubMed and MEDLINE, the subject headings are called Medical Subject Headings (MeSH). By including MeSH terms in your search, you will not have to think about word variations, word endings, plural or singular forms, or synonyms. Some topics or concepts may even have more than one appropriate MeSH term. There are also times when a topic or concept may not have a MeSH term. 

4. Combine concepts using Boolean operators AND/OR

Once you have identified your search concepts, synonyms, and MeSH terms, you'll need to put them together using nesting and Boolean operators (e.g. AND, OR, NOT). Nesting uses parentheses to put search terms into groups. Boolean operators are used to combine similar and different concepts into one query. 

5. Refine search terms and search in PubMed

There are various database search tactics you can use, such as field tags to limit the search to certain fields, quotation marks for phrase searching, and proximity operators to search a number of spaces between terms to refine your search terms. The constructed search string is ready to be pasted into PubMed. 

6. Apply limits (optional)

If you're getting too many results, you can further refine your search results by using limits on the left box of the results page. Limits allow you to narrow your search by a number of facets such as year, journal name, article type, language, age, etc. 

Depending on the nature of the literature review, the complexity and comprehensiveness of the search strategies and the choice of databases can be different. Please contact the Lane Librarians if you have any questions. 

The type of information you gather is influenced by the type of information source or database you select to search. Bibliographic databases contain references to published literature, such as journal articles, conference abstracts, books, reports, government and legal publications, and patents. Literature reviews typically synthesis indexed, peer-reviewed articles (i.e. works that generally represent the latest original research and have undergone rigorous expert screening before publication), and gray literature (i.e. materials not formally published by commercial publishers or peer-reviewed journals). PubMed offers a breadth of health sciences literature and is a good starting point to locate journal articles.

What is PubMed?

PubMed is a free search engine accessing primarily the MEDLINE database of references and abstracts on life sciences and biomedical topics. Available to the public online since 1996, PubMed was developed and is maintained by the  National Center for Biotechnology Information (NCBI) , at the  U.S. National Library of Medicine (NLM) , located at the  National Institutes of Health (NIH) .

MEDLINE is the National Library of Medicine’s (NLM) premier bibliographic database that contains more than 27 million references to journal articles from more than 5,200 worldwide journals in life sciences with a concentration on biomedicine. The Literature Selection Technica Review Committee (LSTRC) reviews and selects journals for MEDLINE based on the research quality and impact of the journals. A distinctive feature of MEDLINE is that the records are indexed with NLM  Medical Subject Headings  (MeSH).

PubMed also contains citations for  PubMed Central (PMC)  articles. PMC is a full-text archive that includes articles from journals reviewed and selected by NLM for archiving (current and historical), as well as individual articles collected for archiving in compliance with funder policies.  PubMed allows users to search keywords in the bibliographic data, but not the full text of the PMC articles.

how to do a literature review pubmed

How to Access PubMed?

To access PubMed, go to the Lane Library homepage and click PubMed in "Top Resources" on the left. This PubMed link is coded with Find Fulltext @ Lane Library Stanford that links you to Lane's full-text articles online. 

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  • Steps in Conducting a Literature Review

What is a literature review?

A literature review is an integrated analysis -- not just a summary-- of scholarly writings and other relevant evidence related directly to your research question.  That is, it represents a synthesis of the evidence that provides background information on your topic and shows a association between the evidence and your research question.

A literature review may be a stand alone work or the introduction to a larger research paper, depending on the assignment.  Rely heavily on the guidelines your instructor has given you.

Why is it important?

A literature review is important because it:

  • Explains the background of research on a topic.
  • Demonstrates why a topic is significant to a subject area.
  • Discovers relationships between research studies/ideas.
  • Identifies major themes, concepts, and researchers on a topic.
  • Identifies critical gaps and points of disagreement.
  • Discusses further research questions that logically come out of the previous studies.

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1. Choose a topic. Define your research question.

Your literature review should be guided by your central research question.  The literature represents background and research developments related to a specific research question, interpreted and analyzed by you in a synthesized way.

  • Make sure your research question is not too broad or too narrow.  Is it manageable?
  • Begin writing down terms that are related to your question. These will be useful for searches later.
  • If you have the opportunity, discuss your topic with your professor and your class mates.

2. Decide on the scope of your review

How many studies do you need to look at? How comprehensive should it be? How many years should it cover? 

  • This may depend on your assignment.  How many sources does the assignment require?

3. Select the databases you will use to conduct your searches.

Make a list of the databases you will search. 

Where to find databases:

  • use the tabs on this guide
  • Find other databases in the Nursing Information Resources web page
  • More on the Medical Library web page
  • ... and more on the Yale University Library web page

4. Conduct your searches to find the evidence. Keep track of your searches.

  • Use the key words in your question, as well as synonyms for those words, as terms in your search. Use the database tutorials for help.
  • Save the searches in the databases. This saves time when you want to redo, or modify, the searches. It is also helpful to use as a guide is the searches are not finding any useful results.
  • Review the abstracts of research studies carefully. This will save you time.
  • Use the bibliographies and references of research studies you find to locate others.
  • Check with your professor, or a subject expert in the field, if you are missing any key works in the field.
  • Ask your librarian for help at any time.
  • Use a citation manager, such as EndNote as the repository for your citations. See the EndNote tutorials for help.

Review the literature

Some questions to help you analyze the research:

  • What was the research question of the study you are reviewing? What were the authors trying to discover?
  • Was the research funded by a source that could influence the findings?
  • What were the research methodologies? Analyze its literature review, the samples and variables used, the results, and the conclusions.
  • Does the research seem to be complete? Could it have been conducted more soundly? What further questions does it raise?
  • If there are conflicting studies, why do you think that is?
  • How are the authors viewed in the field? Has this study been cited? If so, how has it been analyzed?

Tips: 

  • Review the abstracts carefully.  
  • Keep careful notes so that you may track your thought processes during the research process.
  • Create a matrix of the studies for easy analysis, and synthesis, across all of the studies.
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  • How to Write a Literature Review | Guide, Examples, & Templates

How to Write a Literature Review | Guide, Examples, & Templates

Published on January 2, 2023 by Shona McCombes . Revised on September 11, 2023.

What is a literature review? A literature review is a survey of scholarly sources on a specific topic. It provides an overview of current knowledge, allowing you to identify relevant theories, methods, and gaps in the existing research that you can later apply to your paper, thesis, or dissertation topic .

There are five key steps to writing a literature review:

  • Search for relevant literature
  • Evaluate sources
  • Identify themes, debates, and gaps
  • Outline the structure
  • Write your literature review

A good literature review doesn’t just summarize sources—it analyzes, synthesizes , and critically evaluates to give a clear picture of the state of knowledge on the subject.

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Table of contents

What is the purpose of a literature review, examples of literature reviews, step 1 – search for relevant literature, step 2 – evaluate and select sources, step 3 – identify themes, debates, and gaps, step 4 – outline your literature review’s structure, step 5 – write your literature review, free lecture slides, other interesting articles, frequently asked questions, introduction.

  • Quick Run-through
  • Step 1 & 2

When you write a thesis , dissertation , or research paper , you will likely have to conduct a literature review to situate your research within existing knowledge. The literature review gives you a chance to:

  • Demonstrate your familiarity with the topic and its scholarly context
  • Develop a theoretical framework and methodology for your research
  • Position your work in relation to other researchers and theorists
  • Show how your research addresses a gap or contributes to a debate
  • Evaluate the current state of research and demonstrate your knowledge of the scholarly debates around your topic.

Writing literature reviews is a particularly important skill if you want to apply for graduate school or pursue a career in research. We’ve written a step-by-step guide that you can follow below.

Literature review guide

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See an example

how to do a literature review pubmed

Writing literature reviews can be quite challenging! A good starting point could be to look at some examples, depending on what kind of literature review you’d like to write.

  • Example literature review #1: “Why Do People Migrate? A Review of the Theoretical Literature” ( Theoretical literature review about the development of economic migration theory from the 1950s to today.)
  • Example literature review #2: “Literature review as a research methodology: An overview and guidelines” ( Methodological literature review about interdisciplinary knowledge acquisition and production.)
  • Example literature review #3: “The Use of Technology in English Language Learning: A Literature Review” ( Thematic literature review about the effects of technology on language acquisition.)
  • Example literature review #4: “Learners’ Listening Comprehension Difficulties in English Language Learning: A Literature Review” ( Chronological literature review about how the concept of listening skills has changed over time.)

You can also check out our templates with literature review examples and sample outlines at the links below.

Download Word doc Download Google doc

Before you begin searching for literature, you need a clearly defined topic .

If you are writing the literature review section of a dissertation or research paper, you will search for literature related to your research problem and questions .

Make a list of keywords

Start by creating a list of keywords related to your research question. Include each of the key concepts or variables you’re interested in, and list any synonyms and related terms. You can add to this list as you discover new keywords in the process of your literature search.

  • Social media, Facebook, Instagram, Twitter, Snapchat, TikTok
  • Body image, self-perception, self-esteem, mental health
  • Generation Z, teenagers, adolescents, youth

Search for relevant sources

Use your keywords to begin searching for sources. Some useful databases to search for journals and articles include:

  • Your university’s library catalogue
  • Google Scholar
  • Project Muse (humanities and social sciences)
  • Medline (life sciences and biomedicine)
  • EconLit (economics)
  • Inspec (physics, engineering and computer science)

You can also use boolean operators to help narrow down your search.

Make sure to read the abstract to find out whether an article is relevant to your question. When you find a useful book or article, you can check the bibliography to find other relevant sources.

You likely won’t be able to read absolutely everything that has been written on your topic, so it will be necessary to evaluate which sources are most relevant to your research question.

For each publication, ask yourself:

  • What question or problem is the author addressing?
  • What are the key concepts and how are they defined?
  • What are the key theories, models, and methods?
  • Does the research use established frameworks or take an innovative approach?
  • What are the results and conclusions of the study?
  • How does the publication relate to other literature in the field? Does it confirm, add to, or challenge established knowledge?
  • What are the strengths and weaknesses of the research?

Make sure the sources you use are credible , and make sure you read any landmark studies and major theories in your field of research.

You can use our template to summarize and evaluate sources you’re thinking about using. Click on either button below to download.

Take notes and cite your sources

As you read, you should also begin the writing process. Take notes that you can later incorporate into the text of your literature review.

It is important to keep track of your sources with citations to avoid plagiarism . It can be helpful to make an annotated bibliography , where you compile full citation information and write a paragraph of summary and analysis for each source. This helps you remember what you read and saves time later in the process.

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To begin organizing your literature review’s argument and structure, be sure you understand the connections and relationships between the sources you’ve read. Based on your reading and notes, you can look for:

  • Trends and patterns (in theory, method or results): do certain approaches become more or less popular over time?
  • Themes: what questions or concepts recur across the literature?
  • Debates, conflicts and contradictions: where do sources disagree?
  • Pivotal publications: are there any influential theories or studies that changed the direction of the field?
  • Gaps: what is missing from the literature? Are there weaknesses that need to be addressed?

This step will help you work out the structure of your literature review and (if applicable) show how your own research will contribute to existing knowledge.

  • Most research has focused on young women.
  • There is an increasing interest in the visual aspects of social media.
  • But there is still a lack of robust research on highly visual platforms like Instagram and Snapchat—this is a gap that you could address in your own research.

There are various approaches to organizing the body of a literature review. Depending on the length of your literature review, you can combine several of these strategies (for example, your overall structure might be thematic, but each theme is discussed chronologically).

Chronological

The simplest approach is to trace the development of the topic over time. However, if you choose this strategy, be careful to avoid simply listing and summarizing sources in order.

Try to analyze patterns, turning points and key debates that have shaped the direction of the field. Give your interpretation of how and why certain developments occurred.

If you have found some recurring central themes, you can organize your literature review into subsections that address different aspects of the topic.

For example, if you are reviewing literature about inequalities in migrant health outcomes, key themes might include healthcare policy, language barriers, cultural attitudes, legal status, and economic access.

Methodological

If you draw your sources from different disciplines or fields that use a variety of research methods , you might want to compare the results and conclusions that emerge from different approaches. For example:

  • Look at what results have emerged in qualitative versus quantitative research
  • Discuss how the topic has been approached by empirical versus theoretical scholarship
  • Divide the literature into sociological, historical, and cultural sources

Theoretical

A literature review is often the foundation for a theoretical framework . You can use it to discuss various theories, models, and definitions of key concepts.

You might argue for the relevance of a specific theoretical approach, or combine various theoretical concepts to create a framework for your research.

Like any other academic text , your literature review should have an introduction , a main body, and a conclusion . What you include in each depends on the objective of your literature review.

The introduction should clearly establish the focus and purpose of the literature review.

Depending on the length of your literature review, you might want to divide the body into subsections. You can use a subheading for each theme, time period, or methodological approach.

As you write, you can follow these tips:

  • Summarize and synthesize: give an overview of the main points of each source and combine them into a coherent whole
  • Analyze and interpret: don’t just paraphrase other researchers — add your own interpretations where possible, discussing the significance of findings in relation to the literature as a whole
  • Critically evaluate: mention the strengths and weaknesses of your sources
  • Write in well-structured paragraphs: use transition words and topic sentences to draw connections, comparisons and contrasts

In the conclusion, you should summarize the key findings you have taken from the literature and emphasize their significance.

When you’ve finished writing and revising your literature review, don’t forget to proofread thoroughly before submitting. Not a language expert? Check out Scribbr’s professional proofreading services !

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If you want to know more about the research process , methodology , research bias , or statistics , make sure to check out some of our other articles with explanations and examples.

  • Sampling methods
  • Simple random sampling
  • Stratified sampling
  • Cluster sampling
  • Likert scales
  • Reproducibility

 Statistics

  • Null hypothesis
  • Statistical power
  • Probability distribution
  • Effect size
  • Poisson distribution

Research bias

  • Optimism bias
  • Cognitive bias
  • Implicit bias
  • Hawthorne effect
  • Anchoring bias
  • Explicit bias

A literature review is a survey of scholarly sources (such as books, journal articles, and theses) related to a specific topic or research question .

It is often written as part of a thesis, dissertation , or research paper , in order to situate your work in relation to existing knowledge.

There are several reasons to conduct a literature review at the beginning of a research project:

  • To familiarize yourself with the current state of knowledge on your topic
  • To ensure that you’re not just repeating what others have already done
  • To identify gaps in knowledge and unresolved problems that your research can address
  • To develop your theoretical framework and methodology
  • To provide an overview of the key findings and debates on the topic

Writing the literature review shows your reader how your work relates to existing research and what new insights it will contribute.

The literature review usually comes near the beginning of your thesis or dissertation . After the introduction , it grounds your research in a scholarly field and leads directly to your theoretical framework or methodology .

A literature review is a survey of credible sources on a topic, often used in dissertations , theses, and research papers . Literature reviews give an overview of knowledge on a subject, helping you identify relevant theories and methods, as well as gaps in existing research. Literature reviews are set up similarly to other  academic texts , with an introduction , a main body, and a conclusion .

An  annotated bibliography is a list of  source references that has a short description (called an annotation ) for each of the sources. It is often assigned as part of the research process for a  paper .  

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